I found FAKE child support payments in my bfs drawer

Idk what I should do or if it would even be worth bringing up now, or if anything legally could be done now, but earlier this year me and my child’s father split, I moved out of his house and got my own place and our 1 year old son lived with me. A couple months passed and he wasn’t helping much financially with our son at all so I applied for government assistance which I got on the condition of me having to comply with child support against his dad, which I was fine with because he wasn’t helping me anyways. He got served a court date for child support and when he found out he was PISSED and tried for months to get me to drop it all because “he didn’t deserve to be put on child support”. Well we only went to court 2 times and got as far as establishing paternity, never even got to go before the judge and our case was dismissed but I was never told why. Idk how he was able to get out of it he wasn’t even surprised at all that it was dismissed, but after that my assistance was cut off so I lost my job due to not being able to afford child care anymore to go to work and wasn’t making a lot from my job anyways. His dad said that since the child support was dropped he “swore” to help with my bills and diapers etc. since our son lived with me full time. Well he never did that and I couldn’t afford to live on my own and take full care of our child so months later I ended up having to work things out with him and we’ve been doing okay so far. We’re fixing to move into another house and while I was helping him pack, I came across a blank envelope in one of the drawers and peeked in it before throwing it away and seen that it was a stack of check receipts written out by someone and all I saw was the words “child support” I hurried and put the envelope in my waist band before he saw me with them and went to the bathroom to read them to see what they were, it was 16 months worth of FAKE child support payments written out to me!!! Literally 16 months of receipts saying he payed TO THE ORDER OF ME $500 every single month for our son starting the month before he was even born and 11 months before we even split up. I added it all up and it came to 8 THOUSAND dollars that he I guess claimed to have paid me and I never received even a dollar. Isn’t that illegal ?? Whoever wrote them up was smart enough to put on every single receipt that I was paid in cash only so there would have been no way to physically trace back and prove he didn’t pay me that. I’m guessing now that has to be how he managed to wiggle out of court I just can’t believe he wrote up fake ass receipts for an amount that big knowing he never gave me a DIME to support our kid. Should I confront him or what should I do? I honestly only have tried to work things out with him because again I can’t afford to live on my own and work and take care of our son. He only takes care of us when I’m in a relationship with him. I’ve done lost my house and everything and had to move back in with him and be 110% dependent on him. Idk what to even think or what to do or if I should even say anything and cause an argument. What would y’all do?